diff --git a/src/calibre/gui2/book_details.py b/src/calibre/gui2/book_details.py
index 4e3c37afad..8ce18b7dc8 100644
--- a/src/calibre/gui2/book_details.py
+++ b/src/calibre/gui2/book_details.py
@@ -289,7 +289,10 @@ class CoverView(QWidget):  # {{{
         target = QRect(x, y, width, height)
         p = QPainter(self)
         p.setRenderHints(QPainter.Antialiasing | QPainter.SmoothPixmapTransform)
-        dpr = self.devicePixelRatio()
+        try:
+            dpr = self.devicePixelRatioF()
+        except AttributeError:
+            dpr = self.devicePixelRatio()
         spmap = self.pixmap.scaled(target.size() * dpr, Qt.KeepAspectRatio, Qt.SmoothTransformation)
         spmap.setDevicePixelRatio(dpr)
         p.drawPixmap(target, spmap)
diff --git a/src/calibre/gui2/dialogs/book_info.py b/src/calibre/gui2/dialogs/book_info.py
index fdd5425678..520b4edd51 100644
--- a/src/calibre/gui2/dialogs/book_info.py
+++ b/src/calibre/gui2/dialogs/book_info.py
@@ -166,7 +166,10 @@ class BookInfo(QDialog):
                     pixmap.height(), self.cover.size().width()-10,
                     self.cover.size().height()-10)
             if scaled:
-                dpr = self.devicePixelRatio()
+                try:
+                    dpr = self.devicePixelRatioF()
+                except AttributeError:
+                    dpr = self.devicePixelRatio()
                 pixmap = pixmap.scaled(int(dpr * new_width), int(dpr * new_height),
                         Qt.KeepAspectRatio, Qt.SmoothTransformation)
                 pixmap.setDevicePixelRatio(dpr)
@@ -200,7 +203,11 @@ class BookInfo(QDialog):
         self.current_row = row
         self.setWindowTitle(mi.title)
         self.cover_pixmap = QPixmap.fromImage(mi.cover_data[1])
-        self.cover_pixmap.setDevicePixelRatio(self.devicePixelRatio())
+        try:
+            dpr = self.devicePixelRatioF()
+        except AttributeError:
+            dpr = self.devicePixelRatio()
+        self.cover_pixmap.setDevicePixelRatio(dpr)
         self.resize_cover()
         html = render_html(mi, self.css, True, self, all_fields=True)
         self.details.setHtml(html)
diff --git a/src/calibre/gui2/icon_theme.py b/src/calibre/gui2/icon_theme.py
index 6da70effd3..c486e688bf 100644
--- a/src/calibre/gui2/icon_theme.py
+++ b/src/calibre/gui2/icon_theme.py
@@ -688,9 +688,13 @@ class ChooseTheme(Dialog):
 
     def set_cover(self, theme, cdata):
         theme['cover-pixmap'] = p = QPixmap()
+        try:
+            dpr = self.devicePixelRatioF()
+        except AttributeError:
+            dpr = self.devicePixelRatio()
         if isinstance(cdata, bytes):
             p.loadFromData(cdata)
-            p.setDevicePixelRatio(self.devicePixelRatio())
+            p.setDevicePixelRatio(dpr)
         item = self.item_from_name(theme['name'])
         if item is not None:
             item.setData(Qt.DecorationRole, p)
diff --git a/src/calibre/gui2/metadata/pdf_covers.py b/src/calibre/gui2/metadata/pdf_covers.py
index 8d5282e3a7..66e95d552c 100644
--- a/src/calibre/gui2/metadata/pdf_covers.py
+++ b/src/calibre/gui2/metadata/pdf_covers.py
@@ -110,9 +110,14 @@ class PDFCovers(QDialog):
             self.reject()
             return
 
+        try:
+            dpr = self.devicePixelRatioF()
+        except AttributeError:
+            dpr = self.devicePixelRatio()
+
         for i, f in enumerate(sorted(files)):
-            p = QPixmap(f).scaled(self.covers.iconSize()*self.devicePixelRatio(), aspectRatioMode=Qt.IgnoreAspectRatio, transformMode=Qt.SmoothTransformation)
-            p.setDevicePixelRatio(self.devicePixelRatio())
+            p = QPixmap(f).scaled(self.covers.iconSize()*dpr, aspectRatioMode=Qt.IgnoreAspectRatio, transformMode=Qt.SmoothTransformation)
+            p.setDevicePixelRatio(dpr)
             i = QListWidgetItem(_('page %d') % (i + 1))
             i.setData(Qt.DecorationRole, p)
             i.setData(Qt.UserRole, f)
diff --git a/src/calibre/gui2/preferences/look_feel.py b/src/calibre/gui2/preferences/look_feel.py
index b95b02c57e..ba236bb42f 100644
--- a/src/calibre/gui2/preferences/look_feel.py
+++ b/src/calibre/gui2/preferences/look_feel.py
@@ -240,7 +240,11 @@ class Background(QWidget):  # {{{
             path = texture_path(self.btex)
             if path:
                 p = QPixmap(path)
-                p.setDevicePixelRatio(self.devicePixelRatio())
+                try:
+                    dpr = self.devicePixelRatioF()
+                except AttributeError:
+                    dpr = self.devicePixelRatio()
+                p.setDevicePixelRatio(dpr)
                 self.brush.setTexture(p)
         self.update()
 
diff --git a/src/calibre/gui2/tweak_book/editor/canvas.py b/src/calibre/gui2/tweak_book/editor/canvas.py
index 4162418f4a..8278d1f25f 100644
--- a/src/calibre/gui2/tweak_book/editor/canvas.py
+++ b/src/calibre/gui2/tweak_book/editor/canvas.py
@@ -595,7 +595,10 @@ class Canvas(QWidget):
             i = self.current_image
             width, height = i.width(), i.height()
             scaled, width, height = fit_image(width, height, pwidth, pheight)
-            dpr = self.devicePixelRatio()
+            try:
+                dpr = self.devicePixelRatioF()
+            except AttributeError:
+                dpr = self.devicePixelRatio()
             if scaled:
                 i = self.current_image.scaled(int(dpr * width), int(dpr * height), transformMode=Qt.SmoothTransformation)
             self.current_scaled_pixmap = QPixmap.fromImage(i)
@@ -604,7 +607,10 @@ class Canvas(QWidget):
     @painter
     def draw_pixmap(self, painter):
         p = self.current_scaled_pixmap
-        dpr = self.devicePixelRatio()
+        try:
+            dpr = self.devicePixelRatioF()
+        except AttributeError:
+            dpr = self.devicePixelRatio()
         width, height = int(p.width()/dpr), int(p.height()/dpr)
         pwidth, pheight = self.last_canvas_size
         x = int(abs(pwidth - width)/2.)